Effect of land use changes on air quality: Impacts of urbanization, urban vegetation, and agriculture

Urbanization transforms natural landscapes into impervious surfaces, altering local climate and air quality. Greening strategies are increasingly adopted to mitigate these effects, yet their efficacy depends on complex interactions among land use, urban form, geography, and climate. Using an air quality model with an urban canopy scheme, we assess how changes in land use—urban expansion, agriculture, and urban parks—affect urban climate (temperature, wind) and chemical processes (dry deposition, biogenic emissions), ultimately influencing air pollutants (NO2 , O3 , VOC, and PMs). Applied to future land-use scenarios from the Urban Master Plan of the Metropolitan Area of Barcelona, our results show that increasing urbanization elevates surface temperatures and enhances evening O3 levels by up to 8%. Replacing urban areas with agriculture or parks reduces O3 (up to 10%) via increased evapotranspiration and enhanced dry deposition, yet raises NH 3 (up to 90%) and aerosols (up to 12%) from fertilizers. Urban greening increases O3 (up to 5%) and SOA (up to 14%) from biogenic VOCs. Irrigation further boosts plant deposition, raising NO2 and VOCs (up to 10%), and lowering O3 by 6%. Our findings highlight the trade-offs of urban greening and underscore the need for integrated planning to improve air quality.